TECHNICAL FIELD

This invention relates to apparatus for detecting leaks in pipelines, and for an improved detection head for use in combination with leak detection apparatus.

BACKGROUND ART

In conventionally known leak detection systems, the detection head is typically a balloon, and the apparatus includes a flexible line for inflating the balloon to be used for leak detection. The flexible line has to be securely connected to a fluid supply (to inflate the balloon). Connecting the flexible line is typically achieved with standard fittings. Problems may arise when the flexible line is sealed inside a leaking pipe and has to move within the interior of the leaking pipe. The integrity of the balloon at the end of the flexible line has to be maintained whilst also ensuring sufficient pressure is provided to the balloon to allow the balloon to accurately locate the leak. Furthermore, if the pressure exceeds a certain level the balloon may be prone to bursting and/or leaking, meaning it has to be replaced before the leak detection can continue.

Prior art leak detection apparatus, as described in GB2327505, is illustrated schematically in figure 12(a). This apparatus has a reel assembly 241 and pipe means 222. The reel assembly 241 is an open assembly and is entirely exposed to the atmosphere. Connected to one end of pipe means 222 is a detection head 204. In use, leaking pipe 330 is cut upstream of the position of a suspected leak. The mains water supply 200 is connected to an inlet pipe 238 via connection 220 and is henceforth provided to a drive path 250 and a head path 251. Head path 251 passes via valves 232 and pipe 246 to pipe means 222 via a rotational coupling 235 on reel assembly 241. Pipe 222 passes from atmosphere into t-piece 162 via a seal 160. At the end of t-piece is join 221 joining t-piece 162 to pipe 165. At the end of pipe 165 is seal 168 joining pipe 165 to leaking pipe 330. Pipe means 222 passes through seal 160, pipe 162, seal 221 and pipe 165 to head 204 on the end of pipe means 222. The detection head 204 is pressurised to a desired head pressure. Also shown on this figure are exhaust valve 233 and exhaust pipe 245, which are used to lower the pressure in detection head 204 to allow a detection pressure to be set at a desired level; opening valve 232 increases the operating pressure in the detection head, opening valve 233 decreases the operating pressure in the detection head.

Components 162 and 165 are an extension of leaking pipe 330 and are pressurised by drive path 250 (see below).

Concurrently, pressurised water is also provided from the mains water supply inlet 200 to drive path 250. Water in drive path 250 passes via valves 231, 236 and flow gauge 234 into connector arm 163 of t-piece 162. In this way, drive path 250 enters pipes 165 and 330, allowing pressurisation and, when the desired drive pressure is reached, the drive path will push the detection head 204 down the leaking pipe 330 in the method described, more fully in GB2327505. In this prior art apparatus the drive path 250 has no contact with the reel assembly 241, and only meets the pipe means 222 once the pipe means has left the reel assembly 241 and entered t-piece 162 via seal 160.

DISCLOSURE OF INVENTION

According to the invention there is provided a detection head for use in leak detection and/or pipeline analysis apparatus comprising; a front region, a hollow rear end region and a flexible hollow central portion between said front and rear regions, wherein when fluid is introduced into said detection head via said rear region, to apply pressure to said head, said central portion expands radially outwards In a preferred embodiment said front region and said rear region do not undergo any radial or lateral expansion when fluid is introduced into said detection head.

Further preferably, said embodiment comprises interior joining means joining said rear .and front regions inside said central portion.

In another preferred embodiment, there is provided a conduit within said joining means extending from said rear region along at least part of the length of said interior joining means and having at least one exit into said hollow central section.

Preferably, said front region and said rear region are made of metal, and the metal is preferably copper.

In a further preferred embodiment, said front cap and said rear region are fixed to said central section by crimping.

Alternatively, said front and rear regions may be made of plastic and they may be joined to said central portion by vulcanisation, gluing or thermal bonding.

In a further preferred embodiment, said inner joining means is made of longitudinally rigid material.

Further preferably said hollow central section is made of silicone.

In a further preferred embodiment said hollow central section is sufficiently long so that it is able to bend through angles up to 95°.

According to the invention, there is also provided an apparatus for leak detection or pipeline analysis comprising; a pressurisible fluid cavity; pipe means; a detection head; a drive path fluid inlet for providing fluid to a drive path; a head path fluid inlet connected by said pipe means to said detection head along a head path and a fluid outlet for connection to a leaking pipe, through which said drive path passes wherein, in operation; said fluid outlet is connected to a leaking pipe; fluid is provided to both said paths, fluid in said head path passes along said pipe means and fills said detection head to a desired head pressure, fluid in said drive path pressurises said fluid cavity to a desired pressure, once said cavity is pressurised said fluid exits via said fluid outlet and said drive pressure pulls said pipe means out of said pressurised cavity and pushes said pressurised detection head down said leaking pipe.

In a preferred embodiment said apparatus further comprises one or more pressure regulators for regulating pressure within said drive path and/or said head path

In a further preferred embodiment said pressure regulators are located externally of said fluid cavity upstream of said drive path fluid inlet and said head path fluid inlet.

In a further preferred embodiment said air apparatus further comprises air vent means for venting air from said fluid cavity.

BRIEF DESCRIPTION OF DRAWINGS

Preferred embodiments of the invention will now be described, by way of example only with reference to the accompanying drawings in which:

Figure 1(a) shows a front view of one side of the leak detection apparatus;

Figure 1(b) shows a cross-sectional view through the interior of the leak detection apparatus;

Figure 2 shows a side view of the outer case of the leak detection apparatus;

Figure 3 shows a face-on view of the interior of the leak detection apparatus, with the wet cap removed from the outer cover;

Figure 4 is a perspective side-on view corresponding to figure 3;

Figure 5 is a perspective view of the interior of the dry chamber of the apparatus; Figure 6 shows a perspective view of the interior of the wet chamber of the apparatus;

Figure 7 shows a perspective view of the interior surface of the wet cap of the apparatus;

Figure 8 shows a perspective view of the exterior surface of the wet cap of the apparatus;

Figure 9 is a side-on view of a reel assembly used inside the wet chamber of the apparatus;

Figure 10 is a schematic view of the interior of the dry chamber of the apparatus 1 showing the internal components of the dry chamber;

Figure 11(a) shows a cross section of the interior part of a detection head;

Figure 11(b) shows a cross section of the inflatable tube used in the detection head;

Figures 11(c) and (d) show the front and rear pieces that are fitted to the inflatable tube

Figure 11(e) shows how the front and rear pieces are fitted to the detection head:

Figures 11(f) and (g) shows the sideways flexibility of the detection head:

Figure 12(a) shows a schematic flow diagram of the fluid pathway in prior art leak detection system described in patent GB2327505

Figure 12(b) shows a schematic flow diagram of the fluid pathway in the apparatus of figures 1-10;

Figure 13 shows the cross sectional view through the interior of wet chamber of apparatus 1. MODE S FOR CARRYING OUT THE INVENTION

Figures 1-9 show the basic components of a pressurised fluid filled cavity herein described as apparatus 1.

Figure 1(a) is a side view of apparatus 1. The apparatus 1 comprises circular casing 2 with feet 3, and wet cap 5. Wet cap 5 is fixed to circular casing 2 by means of screws 6. A standard O-ring (not shown) is used to ensure a water tight seal between the wet cap 5 and casing 2. The apparatus has a lifting handle 7 on the top of the case 2 and air vent valve 8. Apparatus 1 is also provided with a rotatable handle 9, which is used to retract pipework (not shown) back in via a pipe outlet (not shown). Typically, casing 2, wet cap 5 and feet 3 are made of metal but other materials, such as plastic may be used instead.

In this embodiment, the apparatus is a portable handheld unit. However, the apparatus may be smaller, or may be significantly larger and mounted on a truck for example. These alternative embodiments will be summarised later.

Figure 1(b) is a cross-sectional view of the interior of apparatus 1 showing that it is divided into two distinct chambers, a wet chamber 40 and a dry chamber 30. For clarity these chambers are shown empty. Inlet 20 is connected to dry chamber 30, and in operation a water supply will be connected to inlet 20 to supply water to apparatus 1. Outlet 21 is the output from wet chamber 40, and in operation this outlet 21 will be connected to a leaking pipe. Air vent valve 8 is also positioned on top of wet chamber 40, as wet chamber 40 fills with water the air within the chamber is expelled through valve 8. Similarly when the water is emptied from chamber 40, air returns to chamber 40 via the valve 8. Of course, if the apparatus 1 is being operated pneumatically then air vent valve 8 is not required.

Figure 2 is a side view of the apparatus 1 showing circular casing 2, feet 3 and visual display 10. Display 10 displays pressure and flow information about the apparatus (as described later). Figures 3 and 4 show the interior of wet chamber 40 with the wet cap 5 off, and with a top plate 42 of rotatable reel assembly 41 (described in more detail later) visible. Pipe 22 is coiled around reel assembly 41, and when the apparatus 1 has been used, and pipe 22 is exterior of the casing 2, handle 9 is used to retract pipe 22 back into the casing 2. Handle 9 can be operated manually or may be provided with a motor so it can be driven

automatically.

Figures 5 and 6 are interior perspective views of dry chamber 30 and wet chamber 40 respectively. As can be seen, the two chambers are divided by a central plate 11 which has a central orifice 12 with laterally extending circular walls 12.1, 12.2 on opposite faces of the plate for receiving bearings and seals (as described later). Hole 43 is also positioned towards the edge of plate 11 and passes through the plate to connect the wet and the dry chambers.

Figures 7 and 8 show the interior and exterior surfaces of wet cap 5 respectively. A hole 13 is centrally located in wet cap 5 for receiving the shaft of the reel assembly 41 as described below. Inner laterally extending circular wall 13.2 extends inwardly from hole 13 on the interior side of cap 5. Wall 13.1 extends laterally inwards to hole 13 from the exterior surface of cap 5.

Figure 9 shows reel assembly 41 comprised of central hub 45 and two holding plates 42, 44. Onto the central hub is wound pipe 22 (not shown) which is connected to head 50 (later described). The figure also shows inner shaft 47, rotational coupling 135, bearings 48, locking nut 46 and handle 9. In use, the central hub 45 and holding plates 42, 44 are positioned within the wet chamber 40. Inner shaft 47 passes through hole 13 in wet cap 5, through central hub 45 and out through hole 12 in central plate 11, through locking nut 46 to connect to rotational coupling 135. Handle 9 is secured to the reel assembly 41 by coupling to shaft 47 on the outside of wet cap 5 via hole 13 to allow the reel assembly 41 to be fully rotatable. When reel assembly 41 is in position in chamber 40, bearing 48 adjacent to locking nut 46 is positioned within wall 12.1 of central plate 11, and bearing 48 adjacent the handle 9 is positioned within wall 13.1 on the exterior side of wet cap 5.

Figure 10 shows the different components that make up a drive path 150 and a head path 151.

The various elements in relation to drive path 150 and head path 151 will now be described. In this embodiment, (specifically a portable handheld device) the initial pipework

connecting a mains water supply to the drive 150 and head paths 151 is all contained within the dry chamber 30 of the apparatus 1, and mounted on central plate 11.

Water enters the drive and head paths 150, 151 via inlet 20 on the exterior of case 2. In use, inlet 20 is connected to a mains water supply and outlet 21 connected to a leaking water pipe, upstream of where the leak is suspected to be. Water enters pipe 138 via inlet 20 and after a short distance branches between a drive path 150 via pipe 138 and a head path via pipe 139.

Pressure of water in drive path 150 is regulated via valve 131 and measured via gauge 137a, drive path 150 continues along pipe 140 and reaches valve 136. Valve 136 controls the flow of water in drive path 150 and flow gauge 137c measures the flow of water along pipe 141 Water exits water meter 134 into pipe 141 and through hole 43 into wet chamber 40.

Pressure and flow measurements along drive path 150 are monitored by gauges 137a, 137c. These are conventional analogue or digital devices the output of which can be

monitored/displayed and analysed if necessary. In this apparatus, the outputs are displayed on display unit 10 (Figure 2), but if the valves are analogue then no separate display means are required. Alternatively, the gauges may be connected to a separate computer control system for example. Furthermore, if the apparatus is intended to be used on a large scale it may be partially or fully automated.

If sufficient flow/pressure is provided along drive path 150, wet chamber 40 will fill with water, and air in wet chamber 40 will vent via valve 8. Eventually, wet chamber 40 fills completely with water and the water pressure/flow rate in drive path 150 is sufficient to push detection head 50 and pull pipe 22 through outlet 21 and down the leaking pipe to which outlet 21 has been connected.

Concurrently with this, water passes down head path 151, via pipe 139, control valve 132, pipe 146 and rotational coupling 135. The pressure of water in drive path 151 is measured with gauge 137b; again, the measurement of gauge 137b can be done using analogue or digital means. In this embodiment, the measurement is displayed on unit 10, however, as for gauges 137a and 137c, the valves may be analogue with no separate display, or may be linked to a separate computer control system.

Water in head path 151 then passes through rotational coupling 135, into an end of pipe 22 via a connector (not shown). Head path 151 now passes through pipe 22 coiled around reel assembly 41, and along the length of pipe 22 to head 50 at the end of the pipe 22. The drive pressure and head pressure may be controlled externally by the operator of the apparatus by valves 131, 136, 132 and 133. This control may be manual or automatic, using a computer control system for example. This enables detection head 50 to move along the leaking pipeline to detect the position of the leak.

Figure 13 shows an alternative cross-sectional view through wet chamber 40 of the apparatus 1. This figure shows reel assembly 41, within wet chamber 40 with an end of pipe means 22 also shown. Also shown on this figure is O-ring 40.1 for sealing between the edges of wet chamber 40 and the interior surface of wet cap 5. Central plate 11 is also shown as are seals 47.1, 47.2 and bearings 48 (described previously). The seals 47.1 and 47.2 are set against the inner shaft 47 and are low friction seals which make it much easier for detection head 50 to pull pipe means 22 when the apparatus is fully operational.

Furthermore, the hygiene of the system is improved due to the pipe 22 being enclosed within chamber 40 and not exposed to the external environment. Figures ll(a)-(g) show the various components of the detection head 50. Figures ll(a)-(d) show the component parts of the central section of detection head 50 and figure 11(e) shows the central section in combination with the front and rear pieces. Figure 11(f) and (g) illustrate the flexibility of the central section 52.

In this embodiment, detection head 50 comprises five parts; inner central section 52, inflatable tube 54, front end piece 51, rear end piece 53 and pipe connector 55.

The inner central section 52 consists of ends 70, 71 joined at their inner surfaces 72, 73 by interior pipe means 74. A conduit 77 within pipe means 74, enters through face 76 of end 70 and conduit 77 vents via outlets 78 approximately in the middle of the pipe means 74. As shown, there are two outlets 78, however in alternative embodiments there may be one or more outlets. Outlets 78 can be positioned anywhere along the length of pipe 74, except for on the inner surface 72 of end 70, or anywhere on end 71

The diameter of ends 70, 71 are sized so that they fit snugly against the interior diameter of hollow tube 54, which in turn fits snugly inside recess 53a and 51a in end pieces 53 and 52 respectively _^

To form the detection head 50, central section 52 is inserted into tube 54 and then ends 51, 53 are fitted into place by inserting them over ends 70, 71 respectively

In this preferred embodiment, the front and rear end pieces 51, 53 are typically -lOmm long and the inner central section 52 and hollow tube 54 typically 40mm long, although each of the pieces may be any length greater than ~5mm, and have a diameter greater than -lOmm according to the size of the pipeline to be analysed. More particularly, the detection head 50 can be designed so that it is sized to precisely match the interior diameter of a pipeline to be analysed, this may include detection head less than 10mm is diameter, but typically the diameter range is 10-100mm. The length of end caps 51, 53 is typically determined by the type of join used to fit them to the inflatable tube 54, so a mechanical swage join may require different size end pieces to a join that is chemical by gluing for example.

The crucial dimension is the length of the inflatable tube 54, as this determines the friction between detection head 50 and internal wall of leaking pipe 300 (when the device is in use). The greater the contact area then the greater the friction. This friction varies for different types of pipe, and so the length of detection head 50 depends substantially (but not entirely) on the type of pipeline it will be used in. Furthermore, the operating pressures desired for different environments may also require different lengths of inflatable tube 54.

In this embodiment, inner central section 52 is made of a rigid material (typically plastic) that has lateral flexibility but cannot be longitudinally extended. Inflatable tube 54 is made of silicone and the front and rear pieces are made of metal, typically copper. After inner central section 52 is inserted in inflatable tube 54, front and rear pieces 51, 53 are pushed onto ends 71, 70 respectively and securely held in place by swage fitting them together. This will ensure the join is totally watertight. Alternatively, the front and rear pieces may be made of a plastic material that does not suffer longitudinal deformation, that are joined by vulcanisation, gluing, or any other methods that will provide a watertight join,

In this embodiment, inner central section 52 is made of a rigid material (typically plastic) that has no lateral flexibility and cannot be longitudinally extended. Inflatable tube 54 is typically made of silicone but may be made of rubber or any stretchy material capable of retaining pressurised gasses and liquids. In addition the outer surface of inflatable tube 54 may be coated with a low friction substance such as Teflon; this has a similar effect to changing the length of tube 54 as it affects the amount of friction between detector head 50 and the internal wall of leaking pipe 300 facilitating optimal performance of apparatus 1

The front and rear pieces 51, 53 are made of metal, typically copper. After inner central section 52 is inserted in inflatable tube 54, front and rear pieces 51, 53 are pushed onto ends 71, 70-respectively and securely held in place by swage 51b, 53b, which have smaller internal diameter than the outer diameter of ends 71, 70. This will ensure the join is totally watertight and that end pieces are not pushed off when tube 54 is inflated. Alternatively, the front and rear pieces may be made of a plastic material that does not suffer longitudinal deformation, that are joined by vulcanisation, gluing, or any other methods that will provide a watertight join . Also, if the inflatable tube 54 and central section 52 are glued together then they may be shaped to a particular front/rear profile thus removing the need for separate front and rear pieces

As illustrated in figure 11(f) the inner central section 52 can be made of material or combination of materials that has no longitudinal flexibility but is sufficiently laterally flexible to allow the detection head 50 to travel around short radius bends that may be encountered in the pipework being analysed. Figure 11 (g) illustrates how the same can be achieved by making central section 52 with articulated joint 56 from a completely rigid material that has no longitudinal or lateral flexibility.

In operation detection head 50 is connected to the end of pipe 22 extending out of the outlet 21 by inserting or fixing the end of pipe 22 into pipe connector 55 which is fixed in end of rear piece 53. Water passes down pipe 22 along head path 151 into conduit 77, out of vents 78 and fills tube 54 of head 50 to the desired head pressure. Tube 54 expands radially outwards as it fills, and after sufficient water pressure has been supplied it will contact the internal wall of leaking pipe 300. Although tube 54 expands radially, front and rear pieces 51, 53 do not undergo any expansion or move apart longitudinally as the detection head 50 fills with water.

The pressure of water in drive path 150 can be controlled (via the valves and gauges described with respect to figure 10) to push the detection heads 50 down leaking path 300 to determine the position of the leak in the pipeline 300. Front cap 51 has a domed shape and this ensures it passes down pipe 300 with minimal resistance. The front cap 51 may have alternative profiles (conical, for example) but a curved profile is generally used as this provides a reliable detection head for use in almost all types of pipeline. As mentioned previously, because ends 51, 53 are joined by longitudinally rigid joining section 74, these ends will not deform when head pressure is applied and hollow tube 54 will only expand radially, there will be no longitudinal deformation of any part of detection head 50.

When the drive pressure and detection pressure are set correctly in apparatus 1 either manually or automatically, the drive pressure will push the detection head (set to the detection pressure) down the leaking pipe and the leak can be detected as follows.

Operation of the apparatus will now be described with reference to figure 12(b), showing schematic the flow paths used during leak

Figure 12(b) shows the schematic flow paths of apparatus 1 as herein described, and are similar to that of figure 12(a).

Again, water is provided via mains supply 200 and is used to detect a leak in pipe 300. Mains supply 200 is connected to inlet 20 of apparatus 1. Outlet 21 of apparatus 1 is connected to leaking pipe 300, upstream of the position of the suspected leak. As previously described with reference to figure 10, water is provided to drive path 150 and head path 151 via the various valves and pipe work shown on this figure and fig 10. In this apparatus, as previously described, drive path 151 passes through the wet chamber 40 and exits via outlet 21, the same outlet as for the head path 150. Outlet 21 is connected to pipework 165 and then to leaking pipe 300. The connection between pipes 165 and 300 is sealed with connector 168.

In comparison to the apparatus of GB2327505 apparatus 1 as described above no longer requires the use of t-piece 162 to ensure the drive and head paths 150, 151 both enter the leaking pipe 300. Instead both paths 150, 151 pass out from the fluid outlet 21 of wet chamber 40, head path 151 being fully encapsulated within drive path 150. This means that mechanical seal 160 is eliminated from the apparatus required for the leak detection method. As seal 160 is not required, this removes numerous problems associated with seal point 160, such as surface damage to seal 160 and pipe 222, environmental exposure, friction etc. which are discussed further below.

Apparatus 1 as described allows a moving pressurised pipe to be introduced from outside to a larger static pressurised pipe without the need for a fluid tight seal against the outer pipe wall of the moving pipe, at the point that the smaller pipe enters the larger static pipe.

A major problem with the original configuration in GB2327505 is the damage to pipe 222 as it is repeatedly fed into and then retrieved from leaking pipe (s) 330. The inside of a leaking pipe 330 may contain sharp edges that will eventually lead to damage of the surface of pipe 222 through abrasion. Standard types of seal used for seal 160 require a smooth surface of pipe 222 to seal against, stay fluid tight and hence not leak. Damage of pipe 222 leads to leakage of seal 160 or alternatively the need to tighten the seal against pipe 222 and/or replace. Leakage of the seal reduces the effectiveness of the original leakage detection apparatus as a key feature of the process is the ability to quantify any leak located. If seal 160 is leaking due to damage to pipe 222, this critical feature is impaired requiring the tightening and/or replacement of seal 160 each time the head 204 stops within the leaking pipe. Eventual replacement of pipe 222 at significant cost is required reducing the commercial viability of the original method described.

The prior art system described previously with seal 160 creates an inherent friction on pipe 222 by the seal, which causes a drag force against the drive force exerted on the head 204 by drive path 250. As described in GB2327505the leak detection method requires a balance of drive versus head pressure (flow paths 250 and 251) creating a pressure differential to move head 204. Use of apparatus 1 (elimination of seal 160) reduces drag on head 50 significantly, by removing friction on pipe 22 and allows the pressure required in drive path 150 to move the head 50, to be significantly lower than in the existing system

containing seal 160. System drag will be also increased significantly if the seal is tightened to prevent leakage in 1. In all of the embodiments herein before described, water has been used as the liquid of choice for operating the device. It will be understood, that the apparatus works under the application of hydraulic pressure from any other type of liquid. Furthermore, the apparatus can also be operated pneumatically using various different gases. Also the detection head as herein described can also be used with existing types of currently known and available leak detectors, not solely with the apparatus described herein.

INDUSTRIAL APPLICABILITY OF THE INVENTION

The present invention provides apparatus for detecting leaks and their location,

particularly when situated underground, while avoiding a need for extensive excavation. It thus enables a leak to be located accurately and accessed with minimal displacement of surrounding material and more effective use of man power than has been possible heretofor.